1. Field of the Invention
The present invention relates to a method for recording/reproducing information on an information recording medium. In particular, the present invention relates to a technique for achieving real-time recording/reproduction of video and/or audio data on an information recording medium including a defective region.
2. Description of the Related Art
Optical disks are representative of information recording media having a sector structure. The trend for higher density and larger capacity in recent years has underlined the importance of the reliability of such disks. If a disk includes a sector in which information cannot be properly recorded or reproduced, such a sector is typically registered as a “defective sector” by an optical disk apparatus so that the defective sector will not be used thereafter, and another sector is substituted for that defective sector. This ensures reliability of the disk. Such a defect management function performed by optical disk apparatuses is described in the International Standards Organization ISO/IEC10090 (hereinafter referred to as the “ISO standards”) for 90 mm optical disks.
FIG. 25 is a diagram illustrating the structure of a general disk medium.
The disk medium 1 includes a number of concentric or spiral tracks 2 formed thereon, each track 2 including a number of subdivisions which are referred to as sectors 3. The disk includes two types of regions: disk information areas 4 and a data recording area 5. The disk information areas 4, which store parameters and the like that are necessary for making access to the disk, are positioned at the innermost periphery and the outermost periphery of the disk medium 1.
The disk information areas 4 may also be referred to as lead-in and lead-out areas, respectively. The recording/reproduction of data is performed for the data recording area 5. Every sector in the data recording area 5 receives an absolute address which is referred to as a physical sector number (hereinafter “PSN”).
FIG. 26 illustrates the data structure (denoted as 2600) of a conventional disk medium. The data structure 2600 illustrates a case where, as shown in FIG. 27, the disk medium includes a directory DIR1 under a directory ROOT, and the directory DIR1 includes two files FILE1 and FILE2.
The data structure 2600 includes unused space management information 2601, a data structure 2602 representing the logical space on the disk medium 1, a data structure 2603 representing the physical space on the disk medium 1, and defect management information 2604. The physical space data structure 2603 includes a control data area 2605, defect management information 2606, and an unused spare area 2607, which are to be interpreted only by a reproduction apparatus (e.g., an optical disk drive) for physically reproducing data on the disk medium 1 and which are inaccessible to a control apparatus (e.g., a personal computer). Note that these areas are not included in the logical space data structure 2602.
As shown in FIG. 26, the logical space is divided into a volume structure 2608 for storing logical volume structure information and a region (partition space) 2609 for storing the file structure and file data in the logical volume space. The respective divisions of the logical space are managed based on their consecutive addresses which are referred to as logical sector number (hereinafter “LSN”).
Hereinafter, the respective contents which are stored in the partition space 2609 will be described.
The unused space management information 2601 is a bit map which represents whether each sector within the partition space 2609 is used or not. Each bit on the bit map corresponds to a sector. The bit value “1” indicates “used”, whereas the bit value “0” indicates “unused”. In the example shown in FIG. 26, the unused space management information 2610 and the ROOT directory file structure 2611 always have the “0” bit value on the bit map, whereas all the other regions, except for an unused region 2612, have the “1” bit value on the bit map.
The ROOT directory file structure 2611 includes a ROOT directory file (not shown in the figure) for storing information concerning the files and/or directories which are under the ROOT directory, and a ROOT ICB (not shown in the figure) for specifying a position at which the ROOT directory file is recorded.                A DIR1 file entry 2613 includes the location information of a DIR1 directory file 2614. The DIR1 directory file 2614 stores information concerning the directories and files which are in the directory DIR1.        
The DIR1 directory file 2614 includes information concerning the files FILE1 and FILE2 stored in the directory DIR1, and the location information of a FILE1 file entry 2615 and a FILE2 file entry 2616.
The FILE1 file entry 2615 and the FILE2 file entry 2616 include the location information of the file data of the files FILE1 and FILE2, respectively, and the like.
The FILE1 extent 2617 contains the file data of the file FILE1. The FILE2 extent 2618 contains the file data of the file FILE2.
Next, the physical space data structure 2603 will be described.
The physical space on the disk is generally divided into a disk information area 2619 and a data recording area 2620. The disk information area 2619 stores control information which is referred to only by a reproduction apparatus (e.g., an optical disk drive) for physically reproducing data on the disk medium 1 and is inaccessible to a control apparatus (e.g., a personal computer).
The disk information area 2619 is generally divided into a control data area 2605 and defect management information 2606. The control data area 2605 stores control information such as disk identification information and copyright protection information. The defect management information 2606 stores information concerning any defects on the disk. The defect management information 2606 will be described later in detail.
The data recording area 2620 includes a user area 2621 for recording file structures and file data, and a spare area 2622 for complementing any defective regions which may be present in the user area. A defective region 2623 included within the user area 2621 can be substituted for by a spare region 2624 in the spare area 2622. Similarly, a defective region 2625 included within the user area 2621 can be substituted for by a spare region 2626 in the spare area 2622.
Next, the relationship between the logical space 2602 and the physical space 2603 will be described. If no defective regions are present in the physical space 2603 on the disk, the user area 2621 corresponds to the logical space 2602 for each group. In the example illustrated in FIG. 26, it will be seen that the volume structure 2608, the unused space management information 2610, the ROOT directory file structure 2611, the DIR1 file entry 2613, the DIR1 directory file 2614, the FILE1 file entry 2615, and the FILE2 file entry 2616 in the logical space 2602 correspond to their respective counterparts in the physical space 2603. However, if the physical space 2603 includes any defective regions (e.g., 2623 and 2625), such defective regions (2623 and 2625) can be substituted for by spare regions (e.g., 2624 and 2626) within the spare area 2622. For example, the FILE1 extent region 2617 in the physical space 2603 includes the defective region 2623 in the example illustrated in FIG. 26. Since the defective region 2623 cannot be used, the defective region 2623 is substituted for by the spare region 2624, thereby providing an error-free logical space 2602. As a result, the FILE1 extent 2617 is allocated as one continuous space within the logical space 2602. The same applies to the defective region 2625 in the FILE2 extent 2618 within the physical space 2603.
The defective regions (e.g., 2623 and 2625) and the spare regions (e.g., 2624 and 2626) are managed by the defect management information 2606 within the disk information area 2619. A disk definition structure 2627 of the defect management information 2604 stores information such as a defect management method for the disk and disk attributes. A primary defect list (hereinafter “PDL”) 2628 usually stores the location information of defective regions which are detected during an initialization process performed by a disk manufacturer. Any defective regions which are detected during the use by a user are handled by a secondary defect list (hereinafter “SDL”) 2632. The SDL 2632 includes a secondary defect list header 2629 for storing the number of updates made to the defect management information 2606, a secondary defect list registration number 2630 for indicating the number of pairs of defective regions and corresponding spare regions that are registered in the list (“2” is set in the example illustrated in FIG. 26), and a list 2631 of the PSNs of the defective regions and the PSNs of their corresponding spare regions as arranged in the ascending order of the PSNs of the defective regions. Thus, a recording/reproduction apparatus for the disk reads the defect management information 2604 during a start-up process which is performed upon insertion of the disk, and may access the spare regions, instead of any defective regions, in a subsequent disk access.
Next, a conventional method for performing a recording process for the disk will be described with reference to a flowchart shown in FIG. 28. The recording process can be generally divided into two portions: a file data recording process from Steps 2301 to 2309 and a file structure recording process from Steps 2310 to 2317.
(1) File Data Recording Process
A disk recording apparatus (not shown in the figure) first performs a region allocation Step 2301 for selecting or allocating a location, from within the unused region on the disk, for recording a file. Specifically, a region for recording a file is selected from among the unused regions (which are indicated by the “0” bit value on the aforementioned bit map) in the unused space management information 2601 (FIG. 26). Thus, Step 2301 determines the location of a file to be recorded on the disk. It is assumed that the unused space management information 2601 has previously been read from the disk medium.
Next, at Step 2302, the disk recording apparatus begins recording file data at the recording location which was determined at Step 2301. When performing an actual writing to the disk, an error determination step 2303 checks whether or not a physical address (i.e., location identification information recorded in the form of convexities and concavities on the disk) has been read properly. This check is performed because a sector address must be read before writing data in any given sector. If the sector address which has been read includes an error, the recording cannot occur properly because of inability to identify the right location. If the error determination step 2303 determines that an address read error has occurred, the region associated with the error is defined as a defective region, and an replacement step 2308 is performed.
Next, a verification step 2304 is performed for verifying whether or not a write operation was successfully performed. Specifically, the confirmation of a successful write operation at the verification step 2304 involves reading data from the region for which the write operation was performed, comparing the read data against the data which was intended to be written, calculations associated with error correction codes, and the like.
After the verification step 2304, it is determined at Step 2305 whether or not the data includes an error. If the data includes an error, the region associated with the error is defined as a defective region, and an replacement step 2309 is performed.
If the error determination step 2305 determines no error, it is determined at Step 2306 whether or not all of the data to be recorded has been recorded. If less than all of the data to be recorded has been recorded, a next recording address is set at Step 2307, followed by a data write operation 2302 and a verification step 2304.
The above steps are repeated until all the data to be recorded have been recorded without errors. Thereafter, a file structure recording process is performed.
Note that the replacement steps 2308 and 2309 each involve a process for replacing a defective region with a spare area (e.g., 2622) shown in FIG. 26.
FIG. 29 is a flowchart showing the replacement operation to be performed at the replacement step 2308 or 2309 during recording. At Step 2401, a spare region 2624 or 2626 for substituting for a defective region 2623 or 2625 is allocated from within the spare area 2622 shown in FIG. 26. As a result, at Step 2402, the data which would otherwise have been recorded in the defective region 2623 or 2625 is written in the spare region 2624 or 2626. Thereafter, an error determination step 2403 is performed so as to check whether or not a physical address has been read properly, in a manner similar to Step 2303 described with reference to FIG. 28. If it is determined that the address which has been read includes an error, Steps 2401 and 2402 are performed so as to the perform recording in another spare region. If the write operation is normally ended, a verification step 2404 is performed for verifying whether or not a write operation was successfully performed. Specifically, the confirmation of a successful write operation at the verification step 2404 involves reading data from the region for which the write operation was performed, comparing the read data against the data which was intended to be written, calculations associated with error correction codes, and the like. After the verification step 2404, it is determined at Step 2405 whether or not the data includes an error. If the data includes an error, Step 2401 is again performed to allocate yet another spare region. If the error determination step 2405 determines no error, an SDL registration step 2406 is performed which registers the PSN of the defective region and the PSN of the corresponding spare region on the SDL, and increments the SDL entry number by 1.
(2) File Structure Recording Process
After the file data recording process as described in (1) above is completed, a file structure recording process is performed so as to accommodate any changes in the file data recording locations and any updates made to the size information. The actual file structure recording process is similar to the aforementioned process from Steps 2301 to 2309 except for handling different data contents and recording areas. Specifically, a write operation for the file structure (Step 2310), an address read error determination (Step 2311), a verification (Step 2312), and a verification error determination (Step 2313) are repeated, each time setting a next address (Step 2315), until the process is terminated as a data end is determined (Step 2314).
The replacement processes (Steps 2316 and 2317) which are performed in the case where an error is determined in the error determination Steps (2311 and 2313, respectively) are similar to the replacement step 2308 or 2309 for the aforementioned file data recording process, which have been described with reference to FIG. 29.
(3) Data Reproduction
Next, the operation of reading data which has been recorded in accordance with the recording method illustrated in FIGS. 28 and 29 will be described with reference to FIG. 30. Specifically, FIG. 30 is a flowchart illustrating the operation of reproducing one extent (as part of the file data of the files recorded on a disk). Hereinafter, the respective steps of this process will be described.
Prior to reproduction, a disk reproduction apparatus (not shown in the figure) reads the file structure information at Step 2501. Next, at Step 2502, the file structure which was read at Step 2501 is interpreted so as to obtain therefrom an LSN at which the file data of a file to be reproduced is recorded, as well as the size of that file. Thereafter, at Step 2503, the LSN is converted into a PSN, which is set as a read location. At Step 2504, it is determined whether or not the read location expressed by its PSN has been registered as a defective region PSN on the SDL in the defect management information 2604. If the read location is registered on the SDL as a defective region PSN, the reproduction apparatus calculates the PSN of a spare region which corresponds to the defective region from the SDL, and performs a reproduction process for the spare region at Step 2506. If the read location is not registered as a defective region PSN on the SDL, at Step 2505, the reproduction apparatus performs a reproduction process for the PSN as obtained through the conversion at Step 2503. After the reproduction step 2505 or 2506, the reproduction apparatus determines whether or not all data of the extent which is currently subjected to reproduction has been in fact reproduced at Step 2507. If the reproduction of all of the data is not complete, at Step 2508, a PSN to be reproduced next is set to an address which is obtained by adding the size of data which has been reproduced to the PSN obtained through the aforementioned conversion at Step 2503, and the reproduction process from Step 2504 is repeated. If it is determined at step 2507 that the reproduction of all data of the extent in question is complete, the process is terminated.
However, according to the above-described conventional technique, if the defective region 2623 exists in the FILE1 extent in the data arrangement as shown in FIG. 26, the corresponding spare region 2624 which is allocated within the spare area 2622 will require a seek operation to occur over a considerable distance. For example, in order to continuously reproduce all of the FILE1 extent, portions of the FILE1 extent that are in the user area 2621 are first reproduced. Then, upon encountering the defective region 2623, a seek for the spare area 2622 and a concomitant rotation wait period must occur before the access to the spare region 2624 becomes possible. Similarly, after an access is made to the spare region 2624, a seek from the spare region 2624 back to a region lying subsequent to the defective region 2623 and a concomitant rotation wait period must occur before the access to the remainder of the FILE 1 extent becomes possible. The same also applies to any defective region 2625 in the FILE2 extent.
Thus, a significant delay occurs during a recording or reproduction process if any defective regions (e.g., 2623 or 2625) exist in the user area 2621. It is presumable that such delay may not be critically problematic in the case of disks which are utilized as large-capacity storage media for traditional computer applications. However, such delay may well be critically problematic in real-time recording and/or smooth reproduction of data containing digital video and audio data (hereinafter referred to as “AV data”). For example, problems such as partial loss of AV data, noise generation, inability to perform smooth reproduction, may occur.